Introduction

As developers, every so often we have to kick off some command line programs. Compiling and building tools, utilities,and so on. Recently I have been writing a small application that calls Oracle's 'impdp' and 'expdp' tools for you. While working on it I thought - it'd be nice to see the console program running, but inside my application. This article shows you how to create a Console Control that lets you do just that.

Using the Control

Tip: Use Nuget! Install the package ConsoleControl for WinForms or ConsoleControl.WPF for WPF.

If you just need the control, download the binary and sample application and add a reference to ConsoleControl.dll. You'll get the ConsoleControl in the toolbox, drop it into a Form, and you're done. The key function is:

StartProcess(string fileName, string arguments)

This function starts the process specified by fileName. It will use the arguments supplied. The process will run, but its output will be sent to the console control. The console control can also take input from the keyboard.

Some other useful functions are:

StopProcess

Kills the running process.

WriteOutput(string output, Color color)

Writes the string 'output' to the console window, using the specified color.

WriteInput(string input, bool echo, Color color)

Writes the string 'input' to the running process' input stream. If 'echo' is true, then the input will also be written to the Console Control (as if the user had keyed it in).

ShowDiagnostics

If this property is set to true, diagnostics will be shown. These include:

A message saying 'Running X' when you start a process.

A message saying 'X exited.' when a process ends.

Exceptions written in red if the process cannot be run.

IsInputEnabled

If this property is set to true, then the user can type input into the console window.

IsProcessRunning

This property evaluates to true if the the process is currently running.

CurrentProcess

The current running process (if any).

InternalRichTextBox

Returns the rich text box which displays the console output.

How Does It Work?

Essentially all we need to do to get the required functionality, is create a process and have direct access to its input and output streams. Here's how we can do that. Create a new User Control named 'ConsoleControl' and add a rich text box to the UserControl. Now we'll create the most key function - StartProcess:

The first thing we do is create the process start info. To make sure that it doesn't show a window, we make sure CreateNoWindow is set to true. We will also specify that we're redirecting standard output, standard error, and standard input.

Now that we have the process start info, we can actually start the process. We also store the file name and arguments for later. The class must also contain two background workers, to read the output stream and error stream. Now we start them - and enable editing if the IsInputEnabled flag is on. We also store the standard input, output and error streams.

All we are doing here is reading from the specified buffer. We then use the 'ReportProgress' function of the worker to tell the control to update the screen. The Report Progress event handler works as below:

The event handler is trivial - we just cast the data and write the output. Writing the output is just a case of adding the text to the rich text box. inputStart is also updated - this lets us keep track of where the user can type. This is used in the KeyDown event of the internal rich text box, as we see below.

If the selection is before the input start, we don't let the user enter text. If the return key is pressed, we write it to the output stream.

This is the bulk of the code - as you can see, it is not complex, but it does the job.

Final Thoughts

This control is basic - it may support what you need, if not do feel free to use it as a baseline for your own projects. Some things that the control doesn't do are listed below:

Restrict output to 80 characters horizontally.

Respect changes to the console foreground and background.

Support programmatic clear-screen etc.. Remember - we're streaming output, if you need to run a program that manipulates the console, this is not the control for you!

Ctrl-C

There has been quite some discussion in the messages about the complexity of sending a command like 'Control C' to a cmd process in the console window. Just so that others can find the solution until something formal is actually published, VisualG seems to have a good solution which you can find here:

Comments and Discussions

Hey, thanks for this project. It's really great. I am seeing the Windows Forms version work, but the WPF version is not working for me. I can't even run a basic command. I downloaded your pre-compiled sample. Any idea why that might be?

Hi,
I am using this ConsoleControl to make an IDE in vb.net. So far so good. But i can't start process with this control.
I am making IDE for a scripting language named AutoIt. this is the code for running script with autoit interpreter.

Shell(Autoit_InterPreter_Path & """" & FilenamePath & """")

This is working ok. But in consolecontrol, i need to give second parameter as arguments. Could you please help me ?

because default value of RichTextBox.IsReadOnly is false so you need to set to true if IsInputEnabled is false.

4. I maintain a StringBuilder variable instead of using inputStartPos to get the current input string once user enters Return key. This is because inputStartPos seems to update itself everytime you enter an input, causing the

I want to "StartProcess("java.exe","class_name_here")
But, I can't do it, or maybe you have a way that I don't know... But I'm trying to edit your source code and see the StartProcess() method and I was going to put another argument "WorkingDirectory"... But seems you don't use a System.Diagnostics.Process and ProcessStartInfo there...

How can I use the StartProcess directly to run a java class in a certain directory?

For future references, I found myself with that "situation". The only solution I found was adding the ConsoleControl project and ProcessInterface to my project. Rebuild and there you go, right into the toolbox.

If you are orchestrating some work, you may be in the situation where you need to kick off some command line apps. This can be used to display the output from those apps in a slightly more controlled fashion than just having console windows appear and disappear. Limited use cases but some others have found it useful

If you want a console, there are two options. Kick off a cmd process, or manually build a cmd-like application. The first is definitely much easier. The control might not be the best choice as it's really designed to wrap a running process. If you want to just support readline/writeline, it might be easier to style and customise a rich text box.